Microorganism growth inhibiting fiber products



July 28, 1970 J GANDER ET Al. 3,521,624

MICROORGANISM GROWTH INHIBITING FIBER PRODUCTS Filed July 3. 1967 2 Sheets-Sheet 1 lNVENTORS. Passer d. 644/059 041/0 ZPo 1 55 ATTORNEY.

July 28, 1970 v J. GANDER ET AL 3,521,624

MICRDORGANISM GROWTH INHIBITING FIBER PRODUCTS Filed July 5. 196'? 1 2 Sheets-Sheet 2.

74:2(p vn ATTORNEY.

United States Patent 3,521,624 MICROORGANISM GROWTH INHIBITING FIBER PRODUCTS Robert .I. Gander, Whitehonse, and David T. Rovee, Hopewell, N..I., assignors to Johnson & Johnson, a corporation of New Jersey Filed July 3-, 1967, Ser. No. 650,807 Int. Cl. A61f 5/56 US. Cl. 128-132 18 Claims ABSTRACT OF THE DISCLOSURE Fibers which inhibit growth of microorganisms under damp or humid conditions are prepared by fully or partially coating or impregnating the fibers with a polymeric resin base containing dispersed therethrough a small amount of composition which on reaction with water, generates a compound or compounds which inhibit growth of microorganisms. The preferred compositions are those that react with water to form formaldehyde. The invention is particularly useful in the preparation of dressings and the like where a fiber sheet of woven or nonwoven fabric is to come in contact with the human skin and in fiber absorbent in sheet or batting form used in dressings or other constructions wherein it is desirable to inhibit bacteria growth.

BRIEF SUMMARY OF INVENTION In the preparation of dressings, diapers, absorbent bandages and the like, it has been conventional practice to use cellulosic and similar fibers because of their absorbent character. These are used both as the absorbent component, which may be placed back of a perforate film or other facing, or may form the actual contacting surface with underlying skin such, for example, as where the fibers are formed into a fabric, either woven or nonwoven, or other absorbent sheet material which is to be used in contact with the skin. When such fibers are moist, particularly where the same have absorbed some body exudate, they serve as a, media for bacteria or other microorganism growth. It has heretofore been proposed to treat absorbent fiber products with various germicidal agents in order to inhibit or prevent the growth of microorganisms. However, many such materials, in order to be effective, are required to be present in such concentrations as, in many cases, to be irritating to tissues with which the same may come in contact. Also, there is a susbtantial problem in bonding the antiseptic or other germicidal agent to the fibers so as to make the same remain with the fiber rather than being washed off when in contact with fluids. In accordance with the present invention the fibers are coated either in whole or part with a resin polymer having a composition dispersed therethrough which on reacting with water generates a material which inhibits proliferation of microorganisms. The preferred compositions being those which react with water to release formaldehyde.

Formaldehyde is an effective control material for inhibiting the proliferation of microorganisms such as molds and bacteria in that it denatures the protein in the cell thus destroying the microorganism. The practice of the invention is more particularly described with respect to bacteria proliferation control although the same is not limited thereto.

The resin polymer containing the bacteriostat-generating composition when subjected to humid conditions which would otherwise give a good environment for bacteria growth react with the moisture present to generate and release the bacteriostatic agent. The release of the bacteriostatic agent is thus controlled so that it has little or no 3,521,624 Patented July 28, 1970 ice irriating effect even when the fibers so treated are in intimate contact with underlying living tissue while substantially inhibiting bacteria proliferation in the immediate vicinity of the treated fiber. Such bacteriostat-generating substances are illustrated, for example, by the formaldehyde-generating polymers and polymers that generate alkyl cyano-acetate when reacted with water.

The resin containing the bacteriostat-generating compositions may be coated on individual fibers leaving the fibers free and unbonded to each other or may be used as a bonding agent for bonding the fibers together to form an absorbent fiber pad or a nonwoven fabric.

DESCRIPTION OF INVENTION In practicing the present invention the base polymer is first prepared and the bacteriostat-generating materials then blended therein. The fibers, preferably cellulosic, are then treated with the base polymer containing the bacteriostat-generating composition. The preferred method is to prepare a solution of the polymer, using a solvent which is not reactive with the bacteriostat-generating material and to then disperse the bacteriostat-generating material in the film-forming polymer solution. It is not necessary that the bacteriostat-generating material be soluble in the solvent used. However, care should be taken that it is uniformly dispersed throughout the polymer solution if not soluble therein. The individual fibers or a fiber web may then be treated with the solvent solution by any conventional method such, for example, as by immersion, roll coating, printing, spraying or any of the other wellknown techniques for placing a polymer on a fiber or fiber web.

The polymer in which the bacteriostat-generating material is present should preferably have, when east in film form, a relatively high moisture vapor transmission (M.V.T.) rate or have the ability of absorbing appreciable amounts of moisture. The moisture absorbing ability of the polymer, referred to as moisture affinity, can be substantially improved by dispersing in the polymer a material or materials which have relatively high moisture absorption characteristics. In this manner polymers that might otherwise be unsatisfactory because of their low M.V.T. or low moisture affinity can be used by dispersing therein materials that increase their ability to absorb water. Preferably, the material added to increase the water absorbing characteristics of the polymer is the bacteriostat-generating agent which in such instance would be a compound or polymer that also has the property of absorbing relatively large amounts of water.

Examples of polymers which have relatively high M.V.T. as measured when cast in film thicknesses of about 2 mils and low moisture afiinity are plasticized cellulosic films such as cellulose nitrates, cellulose acetates, ethyl cellulose, and the cellulose acetate butyrate polymer films such as described in US. 'Pat. No. 2,972,545. Polymers having relatively high moisture afiinity but low M.V.T. when in film form are illustrated, for example, by copolymers of vinylidene chloride with more than about 25 weight percent of an oxygen-containing monomer having a molecular weight of less than 150. Examples are a copolymer of 74 weight percent vinylidene chloride and 26 percent ethyl acrylate, and a terpolymer of 65 percent vinylidene chloride, 30 percent n-butyl acrylate and -5 percent acrylic acid.

As previously indicated, both these classes of polymers are well suited for the practice of the present invention,

Illustrative polymers having both low M.V.T. rates when in film form and low moisture aflinity are copolymers of vinyl chloride with less than about 15 weight percent of an oxygen-containing monomer having a molecular weight of less than 150. Examples are a copolymer of weight percent vinyl chloride and 1 5 percent vinyl acetate, and a copolymer of 95 percent vinyl chloride and percent diethyl maleate.

As previously indicated, the moisture affinity of these polymers can be substantially increased by adding to the film-forming polymer a material having a relatively high moisture affinity. Accordingly, when using polymers of the above types which normally give films having low proliferation is shown by the difference in bacteria count obtained under a polymer film without bacteriostat-generating material, which serves as a control, and that under an adjacent polymer film of the same polymer differing only in that it contains the bacteriostat-generating material. This ditference in bacteria count is given in multiples of 10.

TABLE A.-REDUCTION IN BACTERIA COUNT UNDER OCCLUSIVE FILM DRESSINGS THROUGH INCLUSION OF BY WEIGHT OF POLY- (METI'IYL Q-OYANOACRYLATE) Occlusive tests on intact;

CAB, cellulose acetate butyrate; Santieizer 141, 2-ethylhcxyl diphenyl phosphate; V101, vinyl cl1l or1de;ViAc, vinyl acetate; V1012, vinylidene chloride; BA, n-butyl acrylate; AA, acrylic acld; BMA, n-butyl methacrylate; EA, ethyl acrylate; BAOA, N-tert.-butylacrylamido. M.V.T. rates in practicing the present invention, the water absorption of the polymer prepared is increased by including in the polymer a material having the characteristic of absorbing substantial amounts of moisture as their inclusion appears to substantially improve the bacteria growth inhibition obtained, the best results being obtained with polymer composition containing bacteriostat-generating compounds with relatively good water-absorption ability. As an additive material for increasing the waterabsorption characteristics of the polymer film, one may use crosslinked urea-formaldehyde condensation resins, polyvinyl alcohol, polyvinylpyrrolidone, sodium carboxymethyl cellulose, hydroxyethyl cellulose and hydroxypropyl cellulose.

Bacteriostat-generating materials are those compounds and polymers which when reacted with water generate a substance having bacteriostatic properties. The preferred bacteriostat-generating materials of this type are poly mers which react slowly with water to liberate formaldehyde. Some examples of materials of this type are cross linked urea-formaldehyde resins, poly(alkyl 2-cyanoacryl ates) such as poly(methyl 2-cyanoacrylate) and poly(nbutyl 2-cyanoacrylate), and polyvinylidene cyanide.

Materials of the poly(alkyl 2-cyanoacrylate) class when reacted with water not only form formaldehyde, which has bacteriostatic properties, but also form alkyl cyanoacetates, which also exhibit bacteriostatic properties.

In order to demonstrate the bacteria proliferation inhibiting effect of the presence of the polymer with the bacteriostat-generating compound therein, films are prepared of different polymers which have an affinity for cellulosic fibers, i.e., polymers which readily adhere to fibers when coated thereon. These films are then placed in an environment in which bacteria normally multiply rapidly. This environment is obtained by placing over the skin of a subject a piece of vinylidene chloride copolymer film, sold under the name Saran wrap, and having a very low M.V.T. This film is sealed to the underlying skin by taping around the edges with adhesive tape. Under these conditions the bacteria count on the skin under the Saran film is found to increase 10 to 10 times. A piece of film formed of the polymer being tested is then placed in such an environment, both with and without a bacteriostatgenerating agent. The inhibition obtained is well illustrated by the results tabulated in the following Table A. Table A also illustrates the increasing effectiveness of bacteria proliferation inhibition with increasing M.V.T. and particularly with increasing water-absorption rate of polymer used.

The results tabulated in Table A are average results taken from several subjects. The reduction of bacteria The test for bacteria growth inhibition and bacteria counts are obtained in the following manner:

A strip of film of particular polymer composition (control) is placed on the intact skin of a human subject. Over this film is placed another less permeable film (Saran film) and both are taped in p ace. The outer impermeable film serves only to assure the maintenance of a high humidity on the skin, and hence, good conditions for bacterial proliferation. Adjacent to this dressing is placed another film or the same polymer composition and of equal thickness to the control but containing therein the bacteriostat-generating material (experimental film). The experimental film is secured in the same manner as is the control. The film dressings are 2 inches by 2 inches. They are kept in place for 48 hours after which they are removed and bacterial samples immediately taken from the skin areas covered by films. The sample is taken by placing a sterile hollow plastic cylinder covering ca. 700 mm. of skin onto the area of skin to be tested. Into the cylinder is pipetted 1.5 ml. sterile physiological saline and the skin is scraped vigorously with the tip of the pipette for 30 seconds. Then, 1.0 ml. of the saline in the cylinder is removed and placed into a 9 ml. sterile saline blank and appropriate dilutions, generally about 10- made and plated in brain heart infusion agar plus 1% Tween 80. Plates are incubated for 48 hours at 37 C., after which colonies can be counted, the degree of dilution being taken into account.

It becomes readily apparent from examination of the values in the above Table A that the effectiveness of bacteria proliferation is substantially increased as the ability of the polymer to absorb water increases. The water-absorption ability of the polymer is measured by the amount of water absorbed, as shown by an increase in weight, by a film of the polymer after immersion in water for forty-eight hours at a temperature of F. Similar results are obtained when there is substituted for the polymer film, in the above described environment, cotton cloth which has been impregnated with about 1.00 oz. per square yard of polymer, the presence of the bacteriostat-generating material acting, in similar manner, to inhibit bacteria proliferation.

As previously indicated, the water-absorbing ability of the polymer can be substantially increased through the inclusion in the film of a material which itself has a substantial degree of water absorbability. The best results are obtained by including such a material which also will act as the bacteriostat-generating material when wetted. In the following Table B, the inhibition of bacteria growth is shown for polymers in an environment similar to that described with respect to Table A the base polymer compositions being the same as those of Table A but in which the water-absorption ability of the polymer has been substantially increased by including therein a crosslinked urea-formaldehyde condensation resin.

It is believed that formaldehyde is formed by hydrolysis of methylol groups substituted on the nitrogen atoms of the urea units. The hydrolysis reaction occurring on a chain end of the urea-formaldehyde resin may be represented as follows:

HOH

ll NW CHzNC-NCH2OH H2O The material, however, also has a substantial affinity for water in that it readily absorbs the same. In Table B the difference in bacteria count between the polymer film used as a control and that of the same film containing the urea-formaldehyde resin is given. The bacteria count for Table B is obtained in the same manner as that described for Table A. It will be noted that the effectiveness in reducing bacteria growth is substantially enhanced as the water-asborbing properties of the film are increased. Again, similar results are obtained .when there is substituted for the polymer films a nonwoven fabric which has been impregnated with about 1.0 oz. per square yard of polymer, the presence of the bacteriostatgenerating material inhibiting bacteria proliferation.

One of the substantial advantages of the present invention is that the bacteriostat is generated by the moisture surrounding the fibers so treated; thus it is generated at a relatively slow rate which substantially reduces the chance of possible skin irritation. On intact skin no irritation has been noted with dressings containing the bacteriostat-gene'rating materials. With open wounds the underlying surface is more sensitive to irritation then intact skin. Although some slight irritation has been observed in open wounds with some polymer bases having moisture absorption rates of less than 7, where the moisture absorption ability of the polymer base is increased the possibility of irritation is substantially reduced, no irritation whatever having been observed with polymer containing bacteriostat-generating materials which have moisture absorption rates of 20 percent and higher.

Concentrations as low as 1% by weight of poly (methyl Z-cyanoacrylate) in cellulose acetate butyrate polymers, for example, have been found to be effective in reducing bacteria growth. The maximum amount of bacteriostat-generating material in the polymer is apparently limited primarily by the amount of such material that the polymer can contain while still keeping its ability to coat or impregnate the fibers treated. Thus concentrations as high as percent by weight may be used depending on the particular polymer used. The controlled generation and release of such a bacteriostat agent as formaldehyde, for example, particularly with fibers treated with poly- TABLE B.-REDUCTION IN BACTERIA COUNT UNDER OCCLUSIVE FILM DRESSINGS THROUGH INCLUSION OF 10% BY WEIGHT OF UREA- FO RMALDEHYDE RESIN Occlusive tests on intact 48-hr. human skin M.V.T. for water 5-mil films, absorp- Reduction in g./100 sq. tion, bacteria count Film Composition, percent 1 in. [24 hrs. percent over control Irritation SCAN CAB-60 Santicizer G0 43 10X1lIt None VYHH 85 ViCl-15 ViAc 2 7 10X10 Do. 153.--. 65 ViCl2'30 BA-SAA-.- 2 78 10 10 .2 Do. 1171 40 BA-60 ViAc 32 40 10X10 Do. 1167 100 BM 13 27 10 10 Do. 1172-. IDA-50 ViAc 83 81 10 10 Do. 385 6O BA-4O BACA 31 64 l0 10 Do.

1 CAB, cellulose acetate butyrate; Santieizer 141, 2-ethylhexyl diphenyl phosphate;

ViOl, vinyl chloride; ViAc, vinyl acetate; Viclz, AA, acrylic acid; BMA, butylacrylamide.

Particularly useful formaldehyde-generating resins are prepared from the solution of methylol ureas obtained by heating 1.5 to 20 moles of formaldehyde with 1.0 mole of urea at a pH of 7.5 to 9.0. The methylol urea solution is converted to crosslinked resin by acidifying to pH 4.5 with acetic or phosphoric acid and heating. The degree of crosslinking in the resulting resin determines the amount of formaldehyde which it is capable of liberating. Resins which are relatively lightly crosslinked, by mild heating, liberate more formaldehyde than those which have been heated longer and consequently have a higher crosslink density. It is believed that methylol groups are the source of formaldehyde in the resins and that the more highly crosslinked resins have fewer methylol groups because these groups are consumed by the crosslinking reactions. Urea-formaldehyde resin foams are a particularly useful type of resin for the present invention, since they are readily ground to a fine particle size convenient for incorporation in films, and they exhibit high water absorption. The foamed resins may be obtained by adding a surfactant to the acidified solution of methylol ureas, beating to entrap air, and heating the resulting foam to cause condensation and crosslinking such, for example, as described in US. Pat. No. 2,559,891. The urea-formaldehyde resins used in Table B is a foamed of this type, the same giving a formaldehyde release of 40.7 milligrams per gram of resin in 24 hours and 119.8 milligrams of formaldehyde in 96 hours. The in vitro tests, which are made on the polymer itself, are made in the same manner as that hereinafter described.

vinylidene chloride; BA, n-butyl acrylate; n-butyl methacrylate; EA, ethyl acrylate; BACA, N-tert.-

mers having high moisture absorption coefiicients, shows no irritation from the formaldehyde even on open wounds with concentrations as high as 20 percent by weight of the coating polymer. This despite the fact that under normal conditions formaldehyde is a highly irritating material.

In order to more fully illustrate the practice of the present invention, the following examples, as exemplified by the drawings are given. These examples, however, are for the purpose of illustration only and the invention is not limited thereto. The following illustrate the preparation of a bacteriostat polymer and treatment of fibers thereby. The other bacteriostat polymers given as examples as in the specification may be prepared in like manner except that the different monomers and bacteriostat-generating material indicated are used. Thus, for eX- ample, the material, forming the lbandage of FIGS. 8 and 9, is prepared as follows:

A five-liter, three-neck flask is provided with a water condenser, a mechanical stirrer, and a nitrogen inlet tube. The flask is charged with 450 grams of n-butyl acrylate, 300 grams of N-tert.-butylacrylamide, and 1,130 grams of ethyl acetate. During a period of 30 minutes, the contents of the flask are stirred and heated to 75 C. by immersing the flask in an electrically heated oil bath. The inside of the flask is swept with a slow stream of nitrogen during this period. Nitrogen flow is then shut off and 3.75 grams of benzoyl peroxide added. An exothermic reaction ensues, causing the ethyl acetate to reflux vigorously and the reaction mixture to thicken. Stirring and heating in the oil bath at 80-90 C. are continued for 4.0 hours. Ethyl acetate (496 grams) is added to lower the viscosity of the thick reaction mixture. The reaction mixture is then cooled, and samples are dried at 105 C. to determine the solids content and to get a dry sample of the copolymer for viscosity measurements. Solids content of the diluted solution is 31.8 percent. Relative viscosity of the copolymer is 2.70 (1.000 g./ 100 ml., toluene, 30 C.). The polymer is recovered from the solution by casting. it as a film on silicone-coated paper and drying the solvent in an oven.

A pebble mill is charged with 200 parts by weight of a percent ethyl acetate solution of the copolymer and with 4.0 parts of a foamed crosslinked urea-formaldehyde resin having an in vitro formaldehyde release of about 42 milligrams per gram of resin in 24 hours. The ureaformaldehyde resin has a particle size of less than 177 microns (SO-mesh sieve), and pebble milling for eighteen hours reduces the particle size to less than 10 microns. An 80 x 72 count cotton cloth fabric is then coated with the pebble-milled dispersion to a dry pick up weight of about 1 oz. per square yard. This is then rolled and slit into bandage width.

The base polymer containing the bacteriostat-generating compound is hereinafter referred to, for convenience, as the bacteriostat polymer. The manner of incorporating the bacteriostat polymer in the fiber product will depend in part on the nature of the final fiber product to be obtained. Thus, where an absorbent fiber bat is desired in the form of a cotton puff or bat the surface of the cotton bat may be sprayed with a bacteriostat polymer solution. On evaporation of the solvent the bacteriostat polymer is deposited primarily near the surface, bonding surface fibers together to contain the remaining fibers in the bat but 'without causing any substantial compression of the fibers.

Where the fibers containing the bacteriostat polymer are to be contained in a fabric the same may be coated with the bacteriostat polymer by any of the conventional techniques such as immersion coating, calender roll, spraying or printing depending on the degree of coating and the properties desired in the final fabric. Also, where the fabric is one of the nonwoven type in which either a carded or randomly laid web of fibers are bonded with a resin bonding agent, the bacteriostat polymer may be used in place of the regular bonding agent the same being printed on in the pattern desired.

Where the fibers are synthetic, and have themselves been spun from viscose or other resin base, the bacteriostat-generating composition can be ground into a very fine form and dispersed in the resin, prior to extruding the same through spinnerets into fibers.

The practice of the present invention is further illustrated in connection with the accompanying drawings wherein are set forth by way of illustration and example certain embodiments of this invention. Referring to the drawings: 1

FIG. 1 illustrates a cotton puff made in accordance with the present invention;

FIG. 2 is a perspective view of a disposable underpad made in accordance with the present invention;

FIG. 3 is a cross-sectional view taken along lines 33 of FIG. 2;

FIG. 4 is a perspective view of a disposable diaper made in accordance with the present invention;

FIG. 5 is a cross-sectional view taken along lines 5--5 of FIG. 4;

FIG. 6 is a reinforced paper disposable drape made in accordance with the present invention;

FIG. 7 is a crosssectional view taken along lines 77 of FIG. 6;

FIG. 8 is a bandage made in accordance with the present invention;

FIG. 9 is an enlarged sectional view of the material of the bandage of FIG. 8;

FIG. 10 is a perspective view of an adhesive dressing made in accordance with the present invention; and

FIG. 11 is a perspective view taken along lines 1111 of FIG. 10.

Referring to the drawings 10 is a fiber puff or bat made of intertwined cotton or rayon fibers 11. The bat 10 has a relatively low density, the fibers 11 having substantial space therebetween to give the bat 10, a soft resilient feel. The outer fibers are bonded together With a bacteriostat polymer 12 comprising a copolymer of 60' weight percent n-butyl acrylate and 40 percent N-tert.- butylacrylamide containing 10 'weight percent of a ureaformaldehyde resin dispersed therethrough. The bacteriostat polymer is applied by spraying the cotton bat 10 with a dispersion of urea-formaldehyde resin, having a particle size of less than 10 microns, in an ethyl acetate solution of the copolymer, and then evaporating the solvent. The outer fibers 11 of the bat 10 are bonded together to form a fiber net which contains the bat in the shape desired. The solution of bacteriostat polymer, on wetting, also penetrates into the fiber bat 10 to partially coat and bond internal fibers.

In FIG. 2 is illustrated a disposable underpad to be used with bedridden patients. The top of the underpad 13 is formed of a nonwoven fabric 14 impregnated with a bacteriostat polymer which acts to bond the individual fibers of the nonwoven fabric 14 together. The bacteriostat polymer has a copolymer base made from 50 weight percent ethyl acrylate and 50 weight percent vinyl acetate which contains dispersed therethrough 10 weight percent of poly(methyl 2-cyanoacrylate) having a particle size of less than 10 microns.

A bottom sheet 15 formed of a water-impermeable film, such as polyethylene, is secured around the edges of the underpad to the bacteriostat polymer containing cover 14. An absorbent 16 of macerated wood pulp is contained between the cover sheet 14 and the waterimpervious backing sheet 15.

Referring to FIG. 4, there is illustrated a disposable diaper 17. The disposable diaper has a facing 18 of nonwoven fabric formed through the bonding together of a mixture of short and textile-length fibers the same being bonded to each other with a bacteriostat polymer. The facing fabric 18 is prepared by impregnating the fiber web with a solution of the bacteriostat polymer, drawing of excess impregnating solution with vacuum, and then curing the bacteriostat polymer to bond the fibers together. The bacteriostat polymer has a terpolymer base made from 40 weight percent n-butyl acrylate, 47 percent vinyl acetate and 13 percent acrylic acid which contains dispersed therethrough 5 weight percent of a ureaformaldehyde resin having a particle size of less than 10 microns.

The backing sheet 19 of the disposable diaper is formed of a nonwoven fabric having a sheet of polyethylene 20 laminated to the outer surface thereof. Placed between the facing sheet 18 and the backing 19 is interposed an absorbent filler 21 of macerated wood pulp in which a portion of the fibers of the wood pulp contain a bacteriostat polymer. The bacteriostat polymer has a relatively high affinity for moisture and is formed of a copolymer base of Weight percent methyl acrylate and 10 percent acrylic acid containing 5 weight percent of a finelydivided urea-formaldehyde resin dispersed therethrough.

In FIG. 6 is illustrated a scrim-reinforced paper surgical drape 25 wherein the outer surfaces 22 and 23 are formed of paper impregnated with a bacteriostat polymer. Between the two paper facing sheets is placed a fabric scrim 24 made of cross laid strands or, as illustrated in the drawing, an open weave scrim fabric. The reinforcing crossing strands are bonded to the facing paper sheets by bacteriostat polymer similar to that impregnating the paper facing sheets 22 and 23.

In FIG. 9 is illustrated a bandage 26 in roll form 27 with part of the bandage being unrolled. The bandage is formed of woven fabric having a mesh of approximately 80 x 72, the fabric being impregnated with a bacteriostat polymer 27, as best illustrated in the enlarged sectional view of FIG. 9.

FIG. 10 is a perspective view of an adhesive dressing 28 made in accordance with the present invention. The adhesive dressing is of the adhesive bandage type wherein there is a backing strip 29 coated with adhesive 30 and containing in the center portion thereof an absorbent pad 31. As best illustrated in FIG. 11 the absorbent pad is comprised of a facing fabric 32 and an absorbent fiber filler 33. The facing fabric 32 extends around the edges of the fiber filler as illustrated in FIG. 11, the same being held in place by the adhesive 30. The facing fabric is of the nonwoven type in which openings are formed therethrough such, for example, as that described inU.S. Pat. No. 3,081,515. The facing fabric 32 is impregnated with a bacteriostat polymer. The base resin for the bacteriostat polymer is polyvinyl chloride plasticized with a polypropylene adipate to the extent of 67 parts per hundred of resin. The base resin contains 10 weight percent of a urea-formaldehyde resin, particle size less than 10 microns, dispersed in the plasticized polyvinyl chloride.

Several examples of specific products have been given illustrating the practice of the present invention. The invention, however, is not to be limited to the specific examples given but is limited only by the scope of the appended claims.

Having thus described our invention, we claim:

1. In a fiber construction having bacteria proliferation inhibiting properties under moist conditions fibers containing adhered thereto a base polymer having dispersed therethrough a material which reacts with water to give a substance which inhibits bacteria proliferation said material being of the group consisting of crosslinked ureaformaldehyde polymer, poly (alkyl Z-cyanoacrylate), and

polyvinylidene cyanide.

2. A fiber construction of claim 1 in which said material reacts with water to generate formaldehyde.

3. A fiber construction of claim 2 in which said fiber construction is a fiber bat.

4. A fiber construction of claim 3 in which said fiber bat has fibers on its outer surface bonded together with said base polymer.

5. A fiber construction of claim 2 in which said fiber construction is a flexible fiber sheet.

6. A fiber construction of claim 5 in which said fiber sheet is a woven fabric.

7. A fiber construction of claim 5 in which said fiber sheet is a nonwoven sheet.

8. A nonwoven fiber sheet of claim 7 in which fibers are bonded together by said base polymer.

9. An absorbent pad comprising a facing sheet, a backing sheet, and an absorbent contained between said facing sheet and backing sheet, said facing sheet having a fiber construction and being formed of a nonwoven fabric and having bacteria proliferation inhibiting properties under moist conditions the fibers of said nonwoven fabric facing sheet being bonded together by a base polymer having dispersed therethrough a material which reacts with water to generate formaldehyde which inhibits bacteria proliferation.

10. An absorbent pad of claim 9 in which said nonwoven fabric facing sheet is water-pervious and in which said backing sheet is water impervious.

11. An absorbent pad of claim 9 in which said absorbent, contained between said facing sheet and backing sheet, is a fiber absorbent.

12. An absorbent pad of claim 11 in which said fiber absorbent is of cellulosic fibers containing a base polymer having dispersed therethrough a material which reacts with water to give formaldehyde.

13. A surgical drape comprising a reinforced paper formed of interbonded fibers, said paper having the fibers thereof interbonded by a polymer resin said polymer resin having dispersed therethrough a material which reacts with water to give a substance which inhibits bacteria proliferation said material being of the group consisting of crosslinked urea-formaldehyde polymer, poly (alkyl 2- cyanoacrylate), and polyvinylidene cyanide.

14. A surgical drape comprising a first fiber sheet, a second fiber sheet, reinforcing threads extending between said first and second fiber sheets said fiber sheets containing a base polymer having dispersed therethrough a material which reacts with water to give a substance which inhibits bacteria proliferation said material being of the group consisting of crosslinked urea-formaldehyde polymer, poly (alkyl 2-cyanoacrylate), and polyvinylidene cyanide.

15. A dressing comprising a water pervious facing adapted to contact a wound, a backing, and an absorbent between said facing and backing, said facing being formed of cellulosic fibers covered in part with a base polymer having dispersed therethrough a material which reacts with water to give a substance which inhibits bacteria proliferation said material being of the group consisting of crosslinked urea-formaldehyde polymer, poly (alkyl 2- cyanoacrylate), and polyvinylidene cyanide.

16. A dressing of claim 15 in which said backing is an adhesive coated sheet, said facing and said absorbent being secured to said adhesive coated sheet to form an absorbent pad, said adhesive coated backing extending beyond the absorbent pad to provide adhesive coated areas for securing said pad to a patient and removable protective facings extending over the adhesive of said ad hesive coated areas extending beyond said absorbent pad.

17. A fiber construction of claim 1 wherein said material is a crosslinked urea-formaldehyde polymer.

18. A fiber construction of claim 1 in which said polymer is hydrophilic to the extent that in film form it will absorb at least 7 percent by weight of waterin immersion for 48 hours at F.

References Cited UNITED STATES PATENTS 3,187,747 6/ 1965 Burgeni et a1 128285 3,220,960 11/1965 Wichteria et a1. 2602.5 3,406,688 10/1968 Cubitt 128--284 3,423,277 1/1969 Dipner 128-132 ADELE M. EAGER, Primary Examiner US. Cl. X.R. 

